Space Grant Consortium - University of Wisconsin - Green Bay

values are determined through toxicological evaluation performed by Johnson Space Center
(JSC) Scientists. Most offgass concentrations are found safely below the SMAC value, and a
summation formula for toxicity determines how much material or how many units can be flown
safely. Results are entered into a database, the Materials and Process Technical Information
System (MAPTIS), for future reference.
A number of experiments were run to better understand the offgas process, and continue
improving toxicity testing. The main procedure variation was instead of baking the chamber for
72 hours the experimental chambers were baked anywhere between 4 and 24 hours to save time.
The first experiment investigated how combining a volatile organic mix solution and flight
material would affect offgassing. The Mix, material, and a combination of both were placed in
separate chambers and analyzed by identical methods to look for differences in peak areas.
Limits of quantitation (LOQ) tell the minimum amount of analyte that can be quantified by a
particular instrument or method. Offgassing must be quantifiable below its SMAC values to
ensure offgassing can be identified before it poses health hazards. Two Mixes were analyzed for
limits of quantitation by injecting the smallest volume possible that gave integrable peaks.
A response factor, represented by the letter K, is the ratio of compound concentration to the
corresponding peak area. In the past, response factors were calculated with results from flight
hardware, because this was a fast and easy method that gave quality results. In this research
standard volatile organics Mixes were analyzed to compare response factors to standard solutions
as opposed to test data, as well as the difference between the GCs, an Agilent 6890 GC/FID and
Autosystem GC/FID.
Under normal toxicity test procedures, samples cool to ambient room temperature before gas
chromatography analysis. Another experiment looks at the effects of chamber cooling on peak
area. Peak area should decrease over time as the chamber reaches room temperature. Slight
leaks in the chamber could cause the peak areas to decrease slightly over a long period of time
due to offgas loss to the air.
Procedure
Two 5.0g samples of material log number 108053 were weighed in weighing boats. Since the
material was a large piece of cloth, pieces of it were cut until 5.0g was reached. The material
was transferred to 1.00L sealed chambers in the weighing dishes. The chambers had previously
been purged for at least five minutes with high quality air and were examined for seal strength.
Gloves were worn while handling the sample material. A syringe was rinsed once with Mix 4
and used to transfer Mix 4 to two chambers, 30uL to the chamber that already contained 108053,
and 50uL to the chamber with only a weighing bowl.
Only one rinse with volatile organics Mix 4 was used to clean the syringe to conserve the
chemical mix as quantities were limited. Isopropanol was used to rinse the syringe after the Mix
4 had been transferred to the chambers. When not in use Mix 4 was kept in a refrigerator. For
transferring Mix 4, a syringe that had been baked for at least 24 hours was selected.
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